@parcel/core - npm Package Compare versions

Comparing version 2.0.0-nightly.171 to 2.0.0-nightly.175

lib/AssetGraph.js

@@ -19,2 +19,4 @@ "use strict";
 
+var _nullthrows = _interopRequireDefault(require("nullthrows"));
+
 var _Graph = _interopRequireDefault(require("./Graph"));
@@ -93,3 +95,5 @@
   static deserialize(opts) {
-    let res = new AssetGraph(opts);
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
+    let res = new AssetGraph(opts); // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
+
     res.incompleteNodeIds = opts.incompleteNodeIds;
@@ -102,2 +106,3 @@ res.hash = opts.hash;
   serialize() {
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
     return _objectSpread({}, super.serialize(), {
@@ -319,3 +324,3 @@ incompleteNodeIds: this.incompleteNodeIds,
       if (node.type === 'asset') {
-        hash.update(node.value.outputHash);
+        hash.update((0, _nullthrows.default)(node.value.outputHash));
       } else if (node.type === 'dependency' && node.value.target) {
@@ -322,0 +327,0 @@ hash.update(JSON.stringify(node.value.target));

lib/AssetGraphBuilder.js

@@ -257,3 +257,4 @@ "use strict";
 
-    (0, _dumpGraphToGraphViz.default)(this.assetGraph, 'AssetGraph');
+    (0, _dumpGraphToGraphViz.default)(this.assetGraph, 'AssetGraph'); // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
+
     (0, _dumpGraphToGraphViz.default)(this.requestGraph, 'RequestGraph');
@@ -260,0 +261,0 @@ let changedAssets = this.changedAssets;

lib/BundleGraph.js

@@ -504,3 +504,3 @@ "use strict";
     this.traverseAssets(bundle, asset => {
-      hash.update([asset.outputHash, asset.filePath].join(':'));
+      hash.update([asset.outputHash, asset.filePath, asset.type, asset.uniqueKey].join(':'));
     });
@@ -507,0 +507,0 @@ let hashHex = hash.digest('hex');

lib/InternalAsset.js

@@ -9,6 +9,6 @@ "use strict";
 
+var _v = _interopRequireDefault(require("v8"));
+
 var _stream = require("stream");
 
-var _crypto = _interopRequireDefault(require("crypto"));
-
 var _sourceMap = _interopRequireDefault(require("@parcel/source-map"));
@@ -18,2 +18,4 @@
 
+var _nullthrows = _interopRequireDefault(require("nullthrows"));
+
 var _Dependency = require("./Dependency");
@@ -25,2 +27,10 @@
 
+var _loadParcelPlugin = _interopRequireDefault(require("./loadParcelPlugin"));
+
+var _PluginOptions = _interopRequireDefault(require("./public/PluginOptions"));
+
+var _Asset = require("./public/Asset");
+
+var _logger = require("@parcel/logger");
+
 function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
@@ -51,6 +61,8 @@
     mapKey: options.mapKey,
+    astKey: options.astKey,
+    astGenerator: options.astGenerator,
     dependencies: options.dependencies || new Map(),
     includedFiles: options.includedFiles || new Map(),
     isSource: options.isSource,
-    outputHash: options.outputHash || '',
+    outputHash: options.outputHash,
     pipeline: options.pipeline,
@@ -62,3 +74,5 @@ env: options.env,
     sideEffects: options.sideEffects != null ? options.sideEffects : true,
-    uniqueKey: uniqueKey
+    uniqueKey: uniqueKey,
+    plugin: options.plugin,
+    configPath: options.configPath
   };
@@ -74,2 +88,3 @@ }
     ast,
+    isASTDirty,
     idBase
@@ -87,9 +102,14 @@ }) {
 
+    _defineProperty(this, "isASTDirty", void 0);
+
     _defineProperty(this, "idBase", void 0);
 
+    _defineProperty(this, "generatingPromise", void 0);
+
     this.value = value;
     this.options = options;
-    this.content = content || '';
+    this.content = content;
     this.mapBuffer = mapBuffer;
     this.ast = ast;
+    this.isASTDirty = isASTDirty || false;
     this.idBase = idBase;
@@ -104,53 +124,107 @@ }
   async commit(pipelineKey) {
-    this.ast = null;
-    let contentStream = this.getStream();
-
-    if ( // $FlowFixMe
-    typeof contentStream.bytesRead === 'number' && // If the amount of data read from this stream so far isn't exactly the amount
-    // of data that is available to be read, then it has been read from.
-    contentStream.bytesRead !== contentStream.readableLength) {
-      throw new Error('Stream has already been read. This may happen if a plugin reads from a stream and does not replace it.');
+    // If there is a dirty AST, clear out any old content and map as these
+    // must be regenerated later and shouldn't be committed.
+    if (this.ast != null && this.isASTDirty) {
+      this.content = null;
+      this.mapBuffer = null;
     }
 
     let size = 0;
-
-    let hash = _crypto.default.createHash('md5'); // Since we can only read from the stream once, compute the content length
+    let contentKey = this.content == null ? null : this.getCacheKey('content' + pipelineKey);
+    let mapKey = this.mapBuffer == null ? null : this.getCacheKey('map' + pipelineKey);
+    let astKey = this.ast == null ? null : this.getCacheKey('ast' + pipelineKey); // Since we can only read from the stream once, compute the content length
     // and hash while it's being written to the cache.
 
-
-    let [contentKey, mapKey] = await Promise.all([this.options.cache.setStream(this.getCacheKey('content' + pipelineKey), contentStream.pipe(new _utils.TapStream(buf => {
+    await Promise.all([contentKey == null ? Promise.resolve() : this.options.cache.setStream(contentKey, this.getStream().pipe(new _utils.TapStream(buf => {
       size += buf.length;
-      hash.update(buf);
-    }))), this.mapBuffer == null ? Promise.resolve() : this.options.cache.setBlob(this.getCacheKey('map' + pipelineKey), // $FlowFixMe strange that this occurs
-    this.mapBuffer)]);
+    }))), this.mapBuffer == null || mapKey == null ? Promise.resolve() : this.options.cache.setBlob(mapKey, this.mapBuffer), astKey == null ? Promise.resolve() : this.options.cache.setBlob(astKey, // $FlowFixMe
+    _v.default.serialize(this.ast))]);
     this.value.contentKey = contentKey;
     this.value.mapKey = mapKey;
-    this.value.stats.size = size;
-    this.value.outputHash = hash.digest('hex');
+    this.value.astKey = astKey;
+    this.value.outputHash = (0, _utils.md5FromString)([this.value.hash, pipelineKey].join(':')); // TODO: how should we set the size when we only store an AST?
+
+    if (this.content != null) {
+      this.value.stats.size = size;
+    }
   }
 
+  async generateFromAST() {
+    if (this.generatingPromise == null) {
+      this.generatingPromise = this._generateFromAST();
+    }
+
+    await this.generatingPromise;
+    return this.content || '';
+  }
+
+  async _generateFromAST() {
+    let ast = await this.getAST();
+
+    if (ast == null) {
+      throw new Error('Asset has no AST');
+    }
+
+    let pluginName = (0, _nullthrows.default)(this.value.plugin);
+    let plugin = await (0, _loadParcelPlugin.default)(this.options.packageManager, pluginName, (0, _nullthrows.default)(this.value.configPath));
+
+    if (!plugin.generate) {
+      throw new Error(`${pluginName} does not have a generate method`);
+    }
+
+    let {
+      code,
+      map
+    } = await plugin.generate({
+      asset: new _Asset.Asset(this),
+      ast,
+      options: new _PluginOptions.default(this.options),
+      logger: new _logger.PluginLogger({
+        origin: pluginName
+      })
+    });
+    this.content = code;
+    let mapBuffer = this.mapBuffer = map === null || map === void 0 ? void 0 : map.toBuffer(); // Store the results in the cache so we can avoid generating again next time
+
+    await Promise.all([this.options.cache.setStream((0, _nullthrows.default)(this.value.contentKey), this.getStream()), mapBuffer == null ? Promise.resolve() : this.options.cache.setBlob((0, _nullthrows.default)(this.value.mapKey), mapBuffer)]);
+  }
+
+  ensureContent() {
+    let contentKey = this.value.contentKey;
+
+    if (contentKey != null && this.content == null) {
+      // First try the contentKey, and if it doesn't exist, fall back to generating from AST
+      this.content = (0, _utils.fallbackStream)(this.options.cache.getStream(contentKey), () => (0, _utils.streamFromPromise)(this.generateFromAST()));
+    }
+  }
+
   async getCode() {
-    if (this.value.contentKey != null) {
-      this.content = this.options.cache.getStream(this.value.contentKey);
+    if (this.ast != null && this.isASTDirty) {
+      throw new Error('Cannot call getCode() on an asset with a dirty AST. For transformers, implement canReuseAST() and check asset.isASTDirty.');
     }
 
-    if (typeof this.content === 'string' || this.content instanceof Buffer) {
-      this.content = this.content.toString();
-    } else {
-      this.content = (await (0, _utils.bufferStream)(this.content)).toString();
+    this.ensureContent();
+    let content = await this.content;
+
+    if (typeof content === 'string' || content instanceof Buffer) {
+      return content.toString();
+    } else if (content != null) {
+      this.content = (0, _utils.bufferStream)(content);
+      return (await this.content).toString();
     }
 
-    return this.content;
+    return '';
   }
 
   async getBuffer() {
-    if (this.value.contentKey != null) {
-      this.content = this.options.cache.getStream(this.value.contentKey);
-    }
+    this.ensureContent();
+    let content = await this.content;
 
-    if (typeof this.content === 'string' || this.content instanceof Buffer) {
-      return Buffer.from(this.content);
+    if (content == null) {
+      return Buffer.alloc(0);
+    } else if (typeof content === 'string' || content instanceof Buffer) {
+      return Buffer.from(content);
     }
 
-    this.content = await (0, _utils.bufferStream)(this.content);
+    this.content = (0, _utils.bufferStream)(content);
     return this.content;
@@ -160,7 +234,16 @@ }
   getStream() {
-    if (this.value.contentKey != null) {
-      this.content = this.options.cache.getStream(this.value.contentKey);
+    this.ensureContent();
+    let content = this.content;
+
+    if (content instanceof _stream.Readable) {
+      // Remove content if it's a stream, as it should not be reused.
+      this.content = null;
+      return content;
     }
 
-    return (0, _utils.blobToStream)(this.content);
+    if (content instanceof Promise) {
+      return (0, _utils.streamFromPromise)(content);
+    }
+
+    return (0, _utils.blobToStream)(content !== null && content !== void 0 ? content : Buffer.alloc(0));
   }
@@ -170,2 +253,3 @@
     this.content = code;
+    this.clearAST();
   }
@@ -175,2 +259,3 @@
     this.content = buffer;
+    this.clearAST();
   }
@@ -180,7 +265,16 @@
     this.content = stream;
+    this.clearAST();
   }
 
   async getMapBuffer() {
-    if (!this.mapBuffer && this.value.mapKey != null) {
-      this.mapBuffer = await this.options.cache.getBlob(this.value.mapKey);
+    if (this.value.mapKey != null && this.mapBuffer == null) {
+      try {
+        this.mapBuffer = await this.options.cache.getBlob(this.value.mapKey);
+      } catch (err) {
+        if (err.code === 'ENOENT' && this.value.astKey != null) {
+          await this.generateFromAST();
+        } else {
+          throw err;
+        }
+      }
     }
@@ -192,10 +286,10 @@
   async getMap() {
-    if (!this.mapBuffer) {
-      await this.getMapBuffer();
-    }
+    var _this$mapBuffer;
 
-    if (this.mapBuffer) {
+    let mapBuffer = (_this$mapBuffer = this.mapBuffer) !== null && _this$mapBuffer !== void 0 ? _this$mapBuffer : await this.getMapBuffer();
+
+    if (mapBuffer) {
       // Get sourcemap from flatbuffer
       let map = new _sourceMap.default();
-      map.addBufferMappings(this.mapBuffer);
+      map.addBufferMappings(mapBuffer);
       return map;
@@ -211,2 +305,30 @@ }
 
+  async getAST() {
+    if (this.value.astKey != null) {
+      let serializedAst = await this.options.cache.getBlob(this.value.astKey);
+
+      if (serializedAst != null) {
+        // $FlowFixMe
+        this.ast = _v.default.deserialize(serializedAst);
+      }
+    }
+
+    return this.ast;
+  }
+
+  setAST(ast) {
+    this.ast = ast;
+    this.isASTDirty = true;
+    this.value.astGenerator = {
+      type: ast.type,
+      version: ast.version
+    };
+  }
+
+  clearAST() {
+    this.ast = null;
+    this.isASTDirty = false;
+    this.value.astGenerator = null;
+  }
+
   getCacheKey(key) {
@@ -252,24 +374,10 @@ return (0, _utils.md5FromString)(_constants.PARCEL_VERSION + key + this.value.id + (this.value.hash || ''));
 
-  createChildAsset(result) {
+  createChildAsset(result, plugin, configPath) {
     var _ref, _result$content, _result$isIsolated, _result$isInline, _result$isSplittable, _result$isSource, _result$pipeline, _result$sideEffects;
 
-    let content = (_ref = (_result$content = result.content) !== null && _result$content !== void 0 ? _result$content : result.code) !== null && _ref !== void 0 ? _ref : '';
-    let hash;
-    let size;
-
-    if (content === this.content) {
-      hash = this.value.hash;
-      size = this.value.stats.size;
-    } else if (typeof content === 'string' || content instanceof Buffer) {
-      hash = (0, _utils.md5FromString)(content);
-      size = content.length;
-    } else {
-      hash = null;
-      size = NaN;
-    }
-
+    let content = (_ref = (_result$content = result.content) !== null && _result$content !== void 0 ? _result$content : result.code) !== null && _ref !== void 0 ? _ref : null;
     let asset = new InternalAsset({
       value: createAsset({
         idBase: this.idBase,
-        hash,
+        hash: this.value.hash,
         filePath: this.value.filePath,
@@ -288,7 +396,13 @@ type: result.type,
           time: 0,
-          size
+          size: this.value.stats.size
         },
         symbols: new Map([...this.value.symbols, ...(result.symbols || [])]),
         sideEffects: (_result$sideEffects = result.sideEffects) !== null && _result$sideEffects !== void 0 ? _result$sideEffects : this.value.sideEffects,
-        uniqueKey: result.uniqueKey
+        uniqueKey: result.uniqueKey,
+        astGenerator: result.ast ? {
+          type: result.ast.type,
+          version: result.ast.version
+        } : null,
+        plugin,
+        configPath
       }),
@@ -298,2 +412,3 @@ options: this.options,
       ast: result.ast,
+      isASTDirty: result.ast === this.ast ? this.isASTDirty : true,
       mapBuffer: result.map ? result.map.toBuffer() : null,
@@ -300,0 +415,0 @@ idBase: this.idBase

lib/loadDotEnv.js

@@ -43,5 +43,4 @@ "use strict";
     return output.parsed;
-  })); // $FlowFixMe
-
+  }));
   return Object.assign({}, ...envs);
 }

lib/loadParcelConfig.js

@@ -80,3 +80,2 @@ "use strict";
   if (pipeline) {
-    // $FlowFixMe
     return pipeline.map(pkg => {
@@ -83,0 +82,0 @@ if (pkg === '...') return pkg;

lib/Parcel.js

@@ -380,6 +380,8 @@ "use strict";
       } = await _classPrivateFieldGet(this, _assetGraphBuilder).build(signal);
-      (0, _dumpGraphToGraphViz.default)(assetGraph, 'MainAssetGraph');
+      (0, _dumpGraphToGraphViz.default)(assetGraph, 'MainAssetGraph'); // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
+
       let bundleGraph = await _classPrivateFieldGet(this, _bundlerRunner).bundle(assetGraph, {
         signal
-      });
+      }); // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381 (Windows only)
+
       (0, _dumpGraphToGraphViz.default)(bundleGraph._graph, 'BundleGraph');
@@ -386,0 +388,0 @@ await _classPrivateFieldGet(this, _packagerRunner).writeBundles(bundleGraph);

lib/public/Asset.js

@@ -65,6 +65,2 @@ "use strict";
 
-  get ast() {
-    return _classPrivateFieldGet(this, _asset).ast;
-  }
-
   get type() {
@@ -118,2 +114,6 @@ return _classPrivateFieldGet(this, _asset).value.type;
 
+  get astGenerator() {
+    return _classPrivateFieldGet(this, _asset).value.astGenerator;
+  }
+
   getConfig(filePaths, options) {
@@ -151,2 +151,6 @@ return _classPrivateFieldGet(this, _asset).getConfig(filePaths, options);
 
+  getAST() {
+    return _classPrivateFieldGet(this, _asset).getAST();
+  }
+
   getMapBuffer() {
@@ -181,6 +185,2 @@ return _classPrivateFieldGet(this, _asset).getMapBuffer();
 
-  get outputHash() {
-    return _classPrivateFieldGet(this, _asset2).value.outputHash;
-  }
-
   get stats() {
@@ -217,10 +217,2 @@ return _classPrivateFieldGet(this, _asset2).value.stats;
 
-  get ast() {
-    return _classPrivateFieldGet(this, _asset3).ast;
-  }
-
-  set ast(ast) {
-    _classPrivateFieldGet(this, _asset3).ast = ast;
-  }
-
   setMap(map) {
@@ -267,5 +259,9 @@ _classPrivateFieldGet(this, _asset3).setMap(map);
   addIncludedFile(file) {
-    return _classPrivateFieldGet(this, _asset3).addIncludedFile(file);
+    _classPrivateFieldGet(this, _asset3).addIncludedFile(file);
   }
 
+  isASTDirty() {
+    return _classPrivateFieldGet(this, _asset3).isASTDirty;
+  }
+
   setBuffer(buffer) {
@@ -283,2 +279,6 @@ _classPrivateFieldGet(this, _asset3).setBuffer(buffer);
 
+  setAST(ast) {
+    return _classPrivateFieldGet(this, _asset3).setAST(ast);
+  }
+
   addURLDependency(url, opts) {
@@ -285,0 +285,0 @@ return this.addDependency(_objectSpread({

lib/public/Environment.js

@@ -133,3 +133,2 @@ "use strict";
     } else if (this.isNode() && this.engines.node != null && minVersions.node) {
-      // $FlowFixMe
       return !_semver.default.intersects(`< ${minVersions.node}`, this.engines.node);
@@ -136,0 +135,0 @@ }

lib/RequestTracker.js

@@ -62,2 +62,3 @@ "use strict";
   static deserialize(opts) {
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
     let deserialized = new RequestGraph(opts);
@@ -67,3 +68,3 @@ deserialized.invalidNodeIds = opts.invalidNodeIds;
     deserialized.globNodeIds = opts.globNodeIds;
-    deserialized.unpredicatableNodeIds = opts.unpredicatableNodeIds; // $FlowFixMe
+    deserialized.unpredicatableNodeIds = opts.unpredicatableNodeIds; // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381 (Windows only)
 
@@ -70,0 +71,0 @@ return deserialized;

lib/Transformation.js

@@ -44,6 +44,2 @@ "use strict";
 
-function ownKeys(object, enumerableOnly) { var keys = Object.keys(object); if (Object.getOwnPropertySymbols) { var symbols = Object.getOwnPropertySymbols(object); if (enumerableOnly) symbols = symbols.filter(function (sym) { return Object.getOwnPropertyDescriptor(object, sym).enumerable; }); keys.push.apply(keys, symbols); } return keys; }
-
-function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; if (i % 2) { ownKeys(Object(source), true).forEach(function (key) { _defineProperty(target, key, source[key]); }); } else if (Object.getOwnPropertyDescriptors) { Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)); } else { ownKeys(Object(source)).forEach(function (key) { Object.defineProperty(target, key, Object.getOwnPropertyDescriptor(source, key)); }); } } return target; }
-
 function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
@@ -234,3 +230,3 @@
     let inputAssets = [initialAsset];
-    let resultingAssets;
+    let resultingAssets = [];
     let finalAssets = [];
@@ -253,6 +249,6 @@
         try {
-          let transformerResults = await runTransformer(pipeline, asset, transformer.plugin, transformer.name, transformer.config);
+          let transformerResults = await runTransformer(pipeline, asset, transformer.plugin, transformer.name, transformer.config, this.parcelConfig);
 
           for (let result of transformerResults) {
-            resultingAssets.push(asset.createChildAsset(result));
+            resultingAssets.push(asset.createChildAsset(result, transformer.name, this.parcelConfig.filePath));
           }
@@ -267,6 +263,25 @@ } catch (e) {
       inputAssets = resultingAssets;
+    } // Make assets with ASTs generate unless they are js assets and target uses
+    // scope hoisting. This parallelizes generation and distributes work more
+    // evenly across workers than if one worker needed to generate all assets in
+    // a large bundle during packaging.
+
+
+    let generate = pipeline.generate;
+
+    if (generate != null) {
+      await Promise.all(resultingAssets.filter(asset => asset.ast != null && !(asset.value.type === 'js' && asset.value.env.scopeHoist)).map(async asset => {
+        if (asset.isASTDirty) {
+          var _output$map;
+
+          let output = await generate(asset);
+          asset.content = output.code;
+          asset.mapBuffer = (_output$map = output.map) === null || _output$map === void 0 ? void 0 : _output$map.toBuffer();
+        }
+
+        asset.clearAST();
+      }));
     }
 
-    finalAssets = finalAssets.concat(resultingAssets);
-    return Promise.all(finalAssets.map(asset => finalize((0, _nullthrows.default)(asset), (0, _nullthrows.default)(pipeline.generate))));
+    return finalAssets.concat(resultingAssets);
   }
@@ -403,3 +418,3 @@
 
-async function runTransformer(pipeline, asset, transformer, transformerName, preloadedConfig) {
+async function runTransformer(pipeline, asset, transformer, transformerName, preloadedConfig, parcelConfig) {
   const logger = new _logger.PluginLogger({
@@ -432,3 +447,3 @@ origin: transformerName
 
-  if (asset.ast && (!transformer.canReuseAST || !transformer.canReuseAST({
+  if (asset.ast && asset.isASTDirty && (!transformer.canReuseAST || !transformer.canReuseAST({
     ast: asset.ast,
@@ -438,5 +453,7 @@ options: pipeline.pluginOptions,
   })) && pipeline.generate) {
-    let output = await pipeline.generate(new _Asset.MutableAsset(asset));
+    var _output$map2;
+
+    let output = await pipeline.generate(asset);
     asset.content = output.code;
-    asset.ast = null;
+    asset.mapBuffer = (_output$map2 = output.map) === null || _output$map2 === void 0 ? void 0 : _output$map2.toBuffer();
   } // Parse if there is no AST available from a previous transform.
@@ -446,3 +463,3 @@
   if (!asset.ast && transformer.parse) {
-    asset.ast = await transformer.parse({
+    let ast = await transformer.parse({
       asset: new _Asset.MutableAsset(asset),
@@ -454,2 +471,7 @@ config,
     });
+
+    if (ast) {
+      asset.setAST(ast);
+      asset.isASTDirty = false;
+    }
   } // Transform.
@@ -461,2 +483,3 @@
     asset: new _Asset.MutableAsset(asset),
+    ast: asset.ast,
     config,
@@ -469,10 +492,11 @@ options: pipeline.pluginOptions,
   pipeline.generate = input => {
-    if (transformer.generate) {
-      return Promise.resolve(transformer.generate({
-        asset: input,
-        config,
+    if (transformer.generate && input.ast) {
+      let generated = transformer.generate({
+        asset: new _Asset.Asset(input),
+        ast: input.ast,
         options: pipeline.pluginOptions,
-        resolve,
         logger
-      }));
+      });
+      input.clearAST();
+      return Promise.resolve(generated);
     }
@@ -495,3 +519,3 @@
       });
-      return Promise.all(results.map(result => asset.createChildAsset(result)));
+      return Promise.all(results.map(result => asset.createChildAsset(result, transformerName, parcelConfig.filePath)));
     };
@@ -503,16 +527,4 @@ }
 
-async function finalize(asset, generate) {
-  if (asset.ast && generate) {
-    let result = await generate(new _Asset.MutableAsset(asset));
-    return asset.createChildAsset(_objectSpread({
-      type: asset.value.type,
-      uniqueKey: asset.value.uniqueKey
-    }, result));
-  }
-
-  return asset;
-}
-
 function normalizeAssets(results) {
-  return results.map(result => {
+  return Promise.all(results.map(async result => {
     if (!(result instanceof _Asset.MutableAsset)) {
@@ -525,4 +537,4 @@ return result;
       type: result.type,
-      content: internalAsset.content,
-      ast: result.ast,
+      content: await internalAsset.content,
+      ast: internalAsset.ast,
       mapBuffer: internalAsset.mapBuffer,
@@ -540,3 +552,3 @@ // $FlowFixMe
     };
-  });
+  }));
 }
@@ -543,0 +555,0 @@

lib/worker.js

@@ -62,3 +62,2 @@ "use strict";
     report: _ReporterRunner.reportWorker.bind(null, workerApi),
-    // $FlowFixMe
     options,
@@ -84,3 +83,2 @@ config
     report: _ReporterRunner.reportWorker.bind(null, workerApi),
-    // $FlowFixMe
     options,
@@ -107,3 +105,2 @@ config
     config,
-    // $FlowFixMe
     options,
@@ -110,0 +107,0 @@ report: _ReporterRunner.reportWorker.bind(null, workerApi)

package.json

 {
   "name": "@parcel/core",
-  "version": "2.0.0-nightly.171+bac3f05f",
+  "version": "2.0.0-nightly.175+db7e3a12",
   "license": "MIT",
@@ -19,13 +19,13 @@ "publishConfig": {
   "dependencies": {
-    "@parcel/cache": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/diagnostic": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/events": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/fs": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/logger": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/package-manager": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/plugin": "2.0.0-nightly.173+bac3f05f",
+    "@parcel/cache": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/diagnostic": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/events": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/fs": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/logger": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/package-manager": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/plugin": "2.0.0-nightly.177+db7e3a12",
     "@parcel/source-map": "^2.0.0-alpha.4.3",
-    "@parcel/types": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/utils": "2.0.0-nightly.173+bac3f05f",
-    "@parcel/workers": "2.0.0-nightly.173+bac3f05f",
+    "@parcel/types": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/utils": "2.0.0-nightly.177+db7e3a12",
+    "@parcel/workers": "2.0.0-nightly.177+db7e3a12",
     "abortcontroller-polyfill": "^1.1.9",
@@ -46,3 +46,3 @@ "browserslist": "^4.6.6",
   },
-  "gitHead": "bac3f05fa31574338f14ab9cd2c9bd78fb1c22ee"
+  "gitHead": "db7e3a12105630abc44058bff7a88eb612f12e75"
 }

src/AssetGraph.js

@@ -20,2 +20,3 @@ // @flow strict-local
 import {md5FromObject} from '@parcel/utils';
+import nullthrows from 'nullthrows';
 import Graph, {type GraphOpts} from './Graph';
@@ -103,3 +104,5 @@ import {createDependency} from './Dependency';
   static deserialize(opts: SerializedAssetGraph): AssetGraph {
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
     let res = new AssetGraph(opts);
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
     res.incompleteNodeIds = opts.incompleteNodeIds;
@@ -112,2 +115,3 @@ res.hash = opts.hash;
   serialize(): SerializedAssetGraph {
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
     return {
@@ -339,3 +343,3 @@ ...super.serialize(),
       if (node.type === 'asset') {
-        hash.update(node.value.outputHash);
+        hash.update(nullthrows(node.value.outputHash));
       } else if (node.type === 'dependency' && node.value.target) {
@@ -342,0 +346,0 @@ hash.update(JSON.stringify(node.value.target));

src/AssetGraphBuilder.js

@@ -246,2 +246,3 @@ // @flow strict-local
     dumpToGraphViz(this.assetGraph, 'AssetGraph');
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
     dumpToGraphViz(this.requestGraph, 'RequestGraph');
@@ -248,0 +249,0 @@

src/BundleGraph.js

@@ -617,3 +617,7 @@ // @flow strict-local
     this.traverseAssets(bundle, asset => {
-      hash.update([asset.outputHash, asset.filePath].join(':'));
+      hash.update(
+        [asset.outputHash, asset.filePath, asset.type, asset.uniqueKey].join(
+          ':',
+        ),
+      );
     });
@@ -620,0 +624,0 @@

src/InternalAsset.js

@@ -5,2 +5,3 @@ // @flow strict-local
   AST,
+  ASTGenerator,
   Blob,
@@ -13,4 +14,6 @@ ConfigResult,
   PackageJSON,
+  PackageName,
   Stats,
   Symbol,
+  Transformer,
   TransformerResult,
@@ -20,4 +23,4 @@ } from '@parcel/types';
 
+import v8 from 'v8';
 import {Readable} from 'stream';
-import crypto from 'crypto';
 import SourceMap from '@parcel/source-map';
@@ -29,7 +32,14 @@ import {
   blobToStream,
+  streamFromPromise,
+  fallbackStream,
   TapStream,
 } from '@parcel/utils';
+import nullthrows from 'nullthrows';
 import {createDependency, mergeDependencies} from './Dependency';
 import {mergeEnvironments, getEnvironmentHash} from './Environment';
 import {PARCEL_VERSION} from './constants';
+import loadPlugin from './loadParcelPlugin';
+import PluginOptions from './public/PluginOptions';
+import {Asset as PublicAsset} from './public/Asset';
+import {PluginLogger} from '@parcel/logger';
 
@@ -44,2 +54,4 @@ type AssetOptions = {|
   mapKey?: ?string,
+  astKey?: ?string,
+  astGenerator?: ?ASTGenerator,
   dependencies?: Map<string, Dependency>,
@@ -51,5 +63,5 @@ includedFiles?: Map<FilePath, File>,
   isSource: boolean,
-  outputHash?: string,
   env: Environment,
   meta?: Meta,
+  outputHash?: ?string,
   pipeline?: ?string,
@@ -60,2 +72,4 @@ stats: Stats,
   uniqueKey?: ?string,
+  plugin?: PackageName,
+  configPath?: FilePath,
 |};
@@ -81,6 +95,8 @@
     mapKey: options.mapKey,
+    astKey: options.astKey,
+    astGenerator: options.astGenerator,
     dependencies: options.dependencies || new Map(),
     includedFiles: options.includedFiles || new Map(),
     isSource: options.isSource,
-    outputHash: options.outputHash || '',
+    outputHash: options.outputHash,
     pipeline: options.pipeline,
@@ -93,2 +109,4 @@ env: options.env,
     uniqueKey: uniqueKey,
+    plugin: options.plugin,
+    configPath: options.configPath,
   };
@@ -100,5 +118,6 @@ }
   options: ParcelOptions,
-  content?: Blob,
+  content?: ?(Blob | Promise<Buffer>),
   mapBuffer?: ?Buffer,
   ast?: ?AST,
+  isASTDirty?: ?boolean,
   idBase?: ?string,
@@ -110,6 +129,8 @@ |};
   options: ParcelOptions;
-  content: Blob;
+  content: ?(Blob | Promise<Buffer>);
   mapBuffer: ?Buffer;
   ast: ?AST;
+  isASTDirty: boolean;
   idBase: ?string;
+  generatingPromise: ?Promise<void>;
 
@@ -122,2 +143,3 @@ constructor({
     ast,
+    isASTDirty,
     idBase,
@@ -127,5 +149,6 @@ }: InternalAssetOptions) {
     this.options = options;
-    this.content = content || '';
+    this.content = content;
     this.mapBuffer = mapBuffer;
     this.ast = ast;
+    this.isASTDirty = isASTDirty || false;
     this.idBase = idBase;
@@ -139,38 +162,39 @@ }
   async commit(pipelineKey: string): Promise<void> {
-    this.ast = null;
-
-    let contentStream = this.getStream();
-    if (
-      // $FlowFixMe
-      typeof contentStream.bytesRead === 'number' &&
-      // If the amount of data read from this stream so far isn't exactly the amount
-      // of data that is available to be read, then it has been read from.
-      contentStream.bytesRead !== contentStream.readableLength
-    ) {
-      throw new Error(
-        'Stream has already been read. This may happen if a plugin reads from a stream and does not replace it.',
-      );
+    // If there is a dirty AST, clear out any old content and map as these
+    // must be regenerated later and shouldn't be committed.
+    if (this.ast != null && this.isASTDirty) {
+      this.content = null;
+      this.mapBuffer = null;
     }
 
     let size = 0;
-    let hash = crypto.createHash('md5');
+    let contentKey =
+      this.content == null ? null : this.getCacheKey('content' + pipelineKey);
+    let mapKey =
+      this.mapBuffer == null ? null : this.getCacheKey('map' + pipelineKey);
+    let astKey =
+      this.ast == null ? null : this.getCacheKey('ast' + pipelineKey);
 
     // Since we can only read from the stream once, compute the content length
     // and hash while it's being written to the cache.
-    let [contentKey, mapKey] = await Promise.all([
-      this.options.cache.setStream(
-        this.getCacheKey('content' + pipelineKey),
-        contentStream.pipe(
-          new TapStream(buf => {
-            size += buf.length;
-            hash.update(buf);
-          }),
-        ),
-      ),
-      this.mapBuffer == null
+    await Promise.all([
+      contentKey == null
         ? Promise.resolve()
+        : this.options.cache.setStream(
+            contentKey,
+            this.getStream().pipe(
+              new TapStream(buf => {
+                size += buf.length;
+              }),
+            ),
+          ),
+      this.mapBuffer == null || mapKey == null
+        ? Promise.resolve()
+        : this.options.cache.setBlob(mapKey, this.mapBuffer),
+      astKey == null
+        ? Promise.resolve()
         : this.options.cache.setBlob(
-            this.getCacheKey('map' + pipelineKey),
-            // $FlowFixMe strange that this occurs
-            this.mapBuffer,
+            astKey,
+            // $FlowFixMe
+            v8.serialize(this.ast),
           ),
@@ -180,30 +204,102 @@ ]);
     this.value.mapKey = mapKey;
-    this.value.stats.size = size;
-    this.value.outputHash = hash.digest('hex');
+    this.value.astKey = astKey;
+    this.value.outputHash = md5FromString(
+      [this.value.hash, pipelineKey].join(':'),
+    );
+
+    // TODO: how should we set the size when we only store an AST?
+    if (this.content != null) {
+      this.value.stats.size = size;
+    }
   }
 
+  async generateFromAST() {
+    if (this.generatingPromise == null) {
+      this.generatingPromise = this._generateFromAST();
+    }
+
+    await this.generatingPromise;
+    return this.content || '';
+  }
+
+  async _generateFromAST() {
+    let ast = await this.getAST();
+    if (ast == null) {
+      throw new Error('Asset has no AST');
+    }
+
+    let pluginName = nullthrows(this.value.plugin);
+    let plugin: Transformer = await loadPlugin(
+      this.options.packageManager,
+      pluginName,
+      nullthrows(this.value.configPath),
+    );
+    if (!plugin.generate) {
+      throw new Error(`${pluginName} does not have a generate method`);
+    }
+
+    let {code, map} = await plugin.generate({
+      asset: new PublicAsset(this),
+      ast,
+      options: new PluginOptions(this.options),
+      logger: new PluginLogger({origin: pluginName}),
+    });
+
+    this.content = code;
+    let mapBuffer = (this.mapBuffer = map?.toBuffer());
+
+    // Store the results in the cache so we can avoid generating again next time
+    await Promise.all([
+      this.options.cache.setStream(
+        nullthrows(this.value.contentKey),
+        this.getStream(),
+      ),
+      mapBuffer == null
+        ? Promise.resolve()
+        : this.options.cache.setBlob(nullthrows(this.value.mapKey), mapBuffer),
+    ]);
+  }
+
+  ensureContent() {
+    let contentKey = this.value.contentKey;
+    if (contentKey != null && this.content == null) {
+      // First try the contentKey, and if it doesn't exist, fall back to generating from AST
+      this.content = fallbackStream(
+        this.options.cache.getStream(contentKey),
+        () => streamFromPromise(this.generateFromAST()),
+      );
+    }
+  }
+
   async getCode(): Promise<string> {
-    if (this.value.contentKey != null) {
-      this.content = this.options.cache.getStream(this.value.contentKey);
+    if (this.ast != null && this.isASTDirty) {
+      throw new Error(
+        'Cannot call getCode() on an asset with a dirty AST. For transformers, implement canReuseAST() and check asset.isASTDirty.',
+      );
     }
 
-    if (typeof this.content === 'string' || this.content instanceof Buffer) {
-      this.content = this.content.toString();
-    } else {
-      this.content = (await bufferStream(this.content)).toString();
+    this.ensureContent();
+    let content = await this.content;
+
+    if (typeof content === 'string' || content instanceof Buffer) {
+      return content.toString();
+    } else if (content != null) {
+      this.content = bufferStream(content);
+      return (await this.content).toString();
     }
 
-    return this.content;
+    return '';
   }
 
   async getBuffer(): Promise<Buffer> {
-    if (this.value.contentKey != null) {
-      this.content = this.options.cache.getStream(this.value.contentKey);
-    }
+    this.ensureContent();
+    let content = await this.content;
 
-    if (typeof this.content === 'string' || this.content instanceof Buffer) {
-      return Buffer.from(this.content);
+    if (content == null) {
+      return Buffer.alloc(0);
+    } else if (typeof content === 'string' || content instanceof Buffer) {
+      return Buffer.from(content);
     }
 
-    this.content = await bufferStream(this.content);
+    this.content = bufferStream(content);
     return this.content;
@@ -213,7 +309,16 @@ }
   getStream(): Readable {
-    if (this.value.contentKey != null) {
-      this.content = this.options.cache.getStream(this.value.contentKey);
+    this.ensureContent();
+
+    let content = this.content;
+    if (content instanceof Readable) {
+      // Remove content if it's a stream, as it should not be reused.
+      this.content = null;
+      return content;
     }
 
-    return blobToStream(this.content);
+    if (content instanceof Promise) {
+      return streamFromPromise(content);
+    }
+
+    return blobToStream(content ?? Buffer.alloc(0));
   }
@@ -223,2 +328,3 @@
     this.content = code;
+    this.clearAST();
   }
@@ -228,2 +334,3 @@
     this.content = buffer;
+    this.clearAST();
   }
@@ -233,7 +340,16 @@
     this.content = stream;
+    this.clearAST();
   }
 
   async getMapBuffer(): Promise<?Buffer> {
-    if (!this.mapBuffer && this.value.mapKey != null) {
-      this.mapBuffer = await this.options.cache.getBlob(this.value.mapKey);
+    if (this.value.mapKey != null && this.mapBuffer == null) {
+      try {
+        this.mapBuffer = await this.options.cache.getBlob(this.value.mapKey);
+      } catch (err) {
+        if (err.code === 'ENOENT' && this.value.astKey != null) {
+          await this.generateFromAST();
+        } else {
+          throw err;
+        }
+      }
     }
@@ -245,10 +361,7 @@
   async getMap(): Promise<?SourceMap> {
-    if (!this.mapBuffer) {
-      await this.getMapBuffer();
-    }
-
-    if (this.mapBuffer) {
+    let mapBuffer = this.mapBuffer ?? (await this.getMapBuffer());
+    if (mapBuffer) {
       // Get sourcemap from flatbuffer
       let map = new SourceMap();
-      map.addBufferMappings(this.mapBuffer);
+      map.addBufferMappings(mapBuffer);
       return map;
@@ -264,2 +377,29 @@ }
 
+  async getAST(): Promise<?AST> {
+    if (this.value.astKey != null) {
+      let serializedAst = await this.options.cache.getBlob(this.value.astKey);
+      if (serializedAst != null) {
+        // $FlowFixMe
+        this.ast = v8.deserialize(serializedAst);
+      }
+    }
+
+    return this.ast;
+  }
+
+  setAST(ast: AST): void {
+    this.ast = ast;
+    this.isASTDirty = true;
+    this.value.astGenerator = {
+      type: ast.type,
+      version: ast.version,
+    };
+  }
+
+  clearAST() {
+    this.ast = null;
+    this.isASTDirty = false;
+    this.value.astGenerator = null;
+  }
+
   getCacheKey(key: string): string {
@@ -301,22 +441,13 @@ return md5FromString(
 
-  createChildAsset(result: TransformerResult): InternalAsset {
-    let content = result.content ?? result.code ?? '';
+  createChildAsset(
+    result: TransformerResult,
+    plugin: PackageName,
+    configPath: FilePath,
+  ): InternalAsset {
+    let content = result.content ?? result.code ?? null;
 
-    let hash;
-    let size;
-    if (content === this.content) {
-      hash = this.value.hash;
-      size = this.value.stats.size;
-    } else if (typeof content === 'string' || content instanceof Buffer) {
-      hash = md5FromString(content);
-      size = content.length;
-    } else {
-      hash = null;
-      size = NaN;
-    }
-
     let asset = new InternalAsset({
       value: createAsset({
         idBase: this.idBase,
-        hash,
+        hash: this.value.hash,
         filePath: this.value.filePath,
@@ -336,3 +467,2 @@ type: result.type,
           ...this.value.meta,
-          // $FlowFixMe
           ...result.meta,
@@ -345,3 +475,3 @@ },
           time: 0,
-          size,
+          size: this.value.stats.size,
         },
@@ -351,2 +481,7 @@ symbols: new Map([...this.value.symbols, ...(result.symbols || [])]),
         uniqueKey: result.uniqueKey,
+        astGenerator: result.ast
+          ? {type: result.ast.type, version: result.ast.version}
+          : null,
+        plugin,
+        configPath,
       }),
@@ -356,2 +491,3 @@ options: this.options,
       ast: result.ast,
+      isASTDirty: result.ast === this.ast ? this.isASTDirty : true,
       mapBuffer: result.map ? result.map.toBuffer() : null,
@@ -358,0 +494,0 @@ idBase: this.idBase,

src/loadDotEnv.js

@@ -49,4 +49,3 @@ // @flow strict-local
 
-  // $FlowFixMe
   return Object.assign({}, ...envs);
 }

src/loadParcelConfig.js

@@ -85,3 +85,2 @@ // @flow
   if (pipeline) {
-    // $FlowFixMe
     return pipeline.map(pkg => {
@@ -88,0 +87,0 @@ if (pkg === '...') return pkg;

src/Parcel.js

@@ -263,3 +263,5 @@ // @flow strict-local
 
+      // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
       let bundleGraph = await this.#bundlerRunner.bundle(assetGraph, {signal});
+      // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381 (Windows only)
       dumpGraphToGraphViz(bundleGraph._graph, 'BundleGraph');
@@ -266,0 +268,0 @@

src/public/Asset.js

@@ -11,2 +11,3 @@ // @flow strict-local
   AST,
+  ASTGenerator,
   ConfigResult,
@@ -71,6 +72,2 @@ Dependency as IDependency,
 
-  get ast(): ?AST {
-    return this.#asset.ast;
-  }
-
   get type(): string {
@@ -124,2 +121,6 @@ return this.#asset.value.type;
 
+  get astGenerator(): ?ASTGenerator {
+    return this.#asset.value.astGenerator;
+  }
+
   getConfig(
@@ -163,2 +164,6 @@ filePaths: Array<FilePath>,
 
+  getAST(): Promise<?AST> {
+    return this.#asset.getAST();
+  }
+
   getMapBuffer(): Promise<?Buffer> {
@@ -183,6 +188,2 @@ return this.#asset.getMapBuffer();
 
-  get outputHash(): string {
-    return this.#asset.value.outputHash;
-  }
-
   get stats(): Stats {
@@ -207,10 +208,2 @@ return this.#asset.value.stats;
 
-  get ast(): ?AST {
-    return this.#asset.ast;
-  }
-
-  set ast(ast: ?AST): void {
-    this.#asset.ast = ast;
-  }
-
   setMap(map: ?SourceMap): void {
@@ -256,6 +249,10 @@ this.#asset.setMap(map);
 
-  addIncludedFile(file: File) {
-    return this.#asset.addIncludedFile(file);
+  addIncludedFile(file: File): void {
+    this.#asset.addIncludedFile(file);
   }
 
+  isASTDirty(): boolean {
+    return this.#asset.isASTDirty;
+  }
+
   setBuffer(buffer: Buffer): void {
@@ -273,2 +270,6 @@ this.#asset.setBuffer(buffer);
 
+  setAST(ast: AST): void {
+    return this.#asset.setAST(ast);
+  }
+
   addURLDependency(url: string, opts: $Shape<DependencyOptions>): string {
@@ -275,0 +276,0 @@ return this.addDependency({

src/public/Environment.js

@@ -160,3 +160,2 @@ // @flow
     } else if (this.isNode() && this.engines.node != null && minVersions.node) {
-      // $FlowFixMe
       return !semver.intersects(`< ${minVersions.node}`, this.engines.node);
@@ -163,0 +162,0 @@ }

src/RequestTracker.js

@@ -75,2 +75,3 @@ // @flow strict-local
   static deserialize(opts: SerializedRequestGraph) {
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
     let deserialized = new RequestGraph(opts);
@@ -81,3 +82,3 @@ deserialized.invalidNodeIds = opts.invalidNodeIds;
     deserialized.unpredicatableNodeIds = opts.unpredicatableNodeIds;
-    // $FlowFixMe
+    // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381 (Windows only)
     return deserialized;
@@ -84,0 +85,0 @@ }

src/resolveOptions.js

@@ -75,3 +75,2 @@ // @flow strict-local
       ...initialOptions.env,
-      // $FlowFixMe
       ...(await loadDotEnv(
@@ -78,0 +77,0 @@ initialOptions.env ?? {},

src/Transformation.js

 // @flow strict-local
 
 import type {
-  MutableAsset as IMutableAsset,
   FilePath,
@@ -32,3 +31,3 @@ GenerateOutput,
 import ResolverRunner from './ResolverRunner';
-import {MutableAsset, assetToInternalAsset} from './public/Asset';
+import {Asset, MutableAsset, assetToInternalAsset} from './public/Asset';
 import InternalAsset, {createAsset} from './InternalAsset';
@@ -39,3 +38,3 @@ import summarizeRequest from './summarizeRequest';
 
-type GenerateFunc = (input: IMutableAsset) => Promise<GenerateOutput>;
+type GenerateFunc = (input: InternalAsset) => Promise<GenerateOutput>;
 
@@ -240,3 +239,3 @@ type PostProcessFunc = (
     let inputAssets = [initialAsset];
-    let resultingAssets;
+    let resultingAssets = [];
     let finalAssets = [];
@@ -266,6 +265,13 @@ for (let transformer of pipeline.transformers) {
             transformer.config,
+            this.parcelConfig,
           );
 
           for (let result of transformerResults) {
-            resultingAssets.push(asset.createChildAsset(result));
+            resultingAssets.push(
+              asset.createChildAsset(
+                result,
+                transformer.name,
+                this.parcelConfig.filePath,
+              ),
+            );
           }
@@ -281,9 +287,28 @@ } catch (e) {
 
-    finalAssets = finalAssets.concat(resultingAssets);
+    // Make assets with ASTs generate unless they are js assets and target uses
+    // scope hoisting. This parallelizes generation and distributes work more
+    // evenly across workers than if one worker needed to generate all assets in
+    // a large bundle during packaging.
+    let generate = pipeline.generate;
+    if (generate != null) {
+      await Promise.all(
+        resultingAssets
+          .filter(
+            asset =>
+              asset.ast != null &&
+              !(asset.value.type === 'js' && asset.value.env.scopeHoist),
+          )
+          .map(async asset => {
+            if (asset.isASTDirty) {
+              let output = await generate(asset);
+              asset.content = output.code;
+              asset.mapBuffer = output.map?.toBuffer();
+            }
 
-    return Promise.all(
-      finalAssets.map(asset =>
-        finalize(nullthrows(asset), nullthrows(pipeline.generate)),
-      ),
-    );
+            asset.clearAST();
+          }),
+      );
+    }
+
+    return finalAssets.concat(resultingAssets);
   }
@@ -479,2 +504,3 @@
   preloadedConfig: ?Config,
+  parcelConfig: ParcelConfig,
 ): Promise<Array<TransformerResult>> {
@@ -511,2 +537,3 @@ const logger = new PluginLogger({origin: transformerName});
     asset.ast &&
+    asset.isASTDirty &&
     (!transformer.canReuseAST ||
@@ -520,5 +547,5 @@ !transformer.canReuseAST({
   ) {
-    let output = await pipeline.generate(new MutableAsset(asset));
+    let output = await pipeline.generate(asset);
     asset.content = output.code;
-    asset.ast = null;
+    asset.mapBuffer = output.map?.toBuffer();
   }
@@ -528,3 +555,3 @@
   if (!asset.ast && transformer.parse) {
-    asset.ast = await transformer.parse({
+    let ast = await transformer.parse({
       asset: new MutableAsset(asset),
@@ -536,2 +563,6 @@ config,
     });
+    if (ast) {
+      asset.setAST(ast);
+      asset.isASTDirty = false;
+    }
   }
@@ -544,2 +575,3 @@
       asset: new MutableAsset(asset),
+      ast: asset.ast,
       config,
@@ -553,13 +585,12 @@ options: pipeline.pluginOptions,
   // Create generate and postProcess functions that can be called later
-  pipeline.generate = (input: IMutableAsset): Promise<GenerateOutput> => {
-    if (transformer.generate) {
-      return Promise.resolve(
-        transformer.generate({
-          asset: input,
-          config,
-          options: pipeline.pluginOptions,
-          resolve,
-          logger,
-        }),
-      );
+  pipeline.generate = (input: InternalAsset): Promise<GenerateOutput> => {
+    if (transformer.generate && input.ast) {
+      let generated = transformer.generate({
+        asset: new Asset(input),
+        ast: input.ast,
+        options: pipeline.pluginOptions,
+        logger,
+      });
+      input.clearAST();
+      return Promise.resolve(generated);
     }
@@ -586,3 +617,11 @@
 
-      return Promise.all(results.map(result => asset.createChildAsset(result)));
+      return Promise.all(
+        results.map(result =>
+          asset.createChildAsset(
+            result,
+            transformerName,
+            parcelConfig.filePath,
+          ),
+        ),
+      );
     };
@@ -594,43 +633,30 @@ }
 
-async function finalize(
-  asset: InternalAsset,
-  generate: GenerateFunc,
-): Promise<InternalAsset> {
-  if (asset.ast && generate) {
-    let result = await generate(new MutableAsset(asset));
-    return asset.createChildAsset({
-      type: asset.value.type,
-      uniqueKey: asset.value.uniqueKey,
-      ...result,
-    });
-  }
-  return asset;
-}
-
 function normalizeAssets(
   results: Array<TransformerResult | MutableAsset>,
-): Array<TransformerResult> {
-  return results.map(result => {
-    if (!(result instanceof MutableAsset)) {
-      return result;
-    }
+): Promise<Array<TransformerResult>> {
+  return Promise.all(
+    results.map<Promise<TransformerResult>>(async result => {
+      if (!(result instanceof MutableAsset)) {
+        return result;
+      }
 
-    let internalAsset = assetToInternalAsset(result);
-    return {
-      type: result.type,
-      content: internalAsset.content,
-      ast: result.ast,
-      mapBuffer: internalAsset.mapBuffer,
-      // $FlowFixMe
-      dependencies: [...internalAsset.value.dependencies.values()],
-      includedFiles: result.getIncludedFiles(),
-      // $FlowFixMe
-      env: result.env,
-      isIsolated: result.isIsolated,
-      isInline: result.isInline,
-      pipeline: internalAsset.value.pipeline,
-      meta: result.meta,
-      uniqueKey: internalAsset.value.uniqueKey,
-    };
-  });
+      let internalAsset = assetToInternalAsset(result);
+      return {
+        type: result.type,
+        content: await internalAsset.content,
+        ast: internalAsset.ast,
+        mapBuffer: internalAsset.mapBuffer,
+        // $FlowFixMe
+        dependencies: [...internalAsset.value.dependencies.values()],
+        includedFiles: result.getIncludedFiles(),
+        // $FlowFixMe
+        env: result.env,
+        isIsolated: result.isIsolated,
+        isInline: result.isInline,
+        pipeline: internalAsset.value.pipeline,
+        meta: result.meta,
+        uniqueKey: internalAsset.value.uniqueKey,
+      };
+    }),
+  );
 }
@@ -637,0 +663,0 @@

src/types.js

 // @flow strict-local
 
 import type {
+  ASTGenerator,
   BuildMode,
@@ -111,3 +112,2 @@ BundleGroup,
   isSource: boolean,
-  outputHash: string,
   env: Environment,
@@ -118,6 +118,11 @@ meta: Meta,
   mapKey: ?string,
+  outputHash: ?string,
   pipeline: ?string,
+  astKey: ?string,
+  astGenerator: ?ASTGenerator,
   symbols: Map<Symbol, Symbol>,
   sideEffects: boolean,
   uniqueKey?: ?string,
+  configPath?: FilePath,
+  plugin?: ?PackageName,
 |};
@@ -124,0 +129,0 @@

src/worker.js

@@ -51,3 +51,2 @@ // @flow strict-local
     report: reportWorker.bind(null, workerApi),
-    // $FlowFixMe
     options,
@@ -74,3 +73,2 @@ config,
     report: reportWorker.bind(null, workerApi),
-    // $FlowFixMe
     options,
@@ -116,3 +114,2 @@ config,
     config,
-    // $FlowFixMe
     options,
@@ -119,0 +116,0 @@ report: reportWorker.bind(null, workerApi),

test/loadParcelConfig.test.js

@@ -86,5 +86,5 @@ // @flow
         validateConfigFile(
+          // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
           {
             filePath: '.parcelrc',
-            // $FlowFixMe
             resolvers: '123',
@@ -115,3 +115,2 @@ },
             filePath: '.parcelrc',
-            // $FlowFixMe
             resolvers: ['parcel-foo-bar'],
@@ -128,3 +127,2 @@ },
           filePath: '.parcelrc',
-          // $FlowFixMe
           resolvers: ['parcel-resolver-test'],
@@ -140,3 +138,2 @@ },
           filePath: '.parcelrc',
-          // $FlowFixMe
           resolvers: ['parcel-resolver-test', '...'],
@@ -179,5 +176,5 @@ },
         validateConfigFile(
+          // $FlowFixMe Added in Flow 0.121.0 upgrade in #4381
           {
             filePath: '.parcelrc',
-            // $FlowFixMe
             extends: 2,
@@ -184,0 +181,0 @@ },

New alerts

Manifest confusion

Supply chain risk

This package has inconsistent metadata. This could be malicious or caused by an error when publishing the package.

Found 1 instance in 1 package

Fixed alerts

Manifest confusion

Supply chain risk

This package has inconsistent metadata. This could be malicious or caused by an error when publishing the package.

Found 1 instance in 1 package

Improved metrics

Total package byte prevSize

693308

increased by1.4%

Lines of code

19815

increased by1.31%

Worsened metrics

Number of low supply chain risk alerts

8

increased by33.33%

Dependency changes

• Updated@parcel/cache@2.0.0-nightly.177+db7e3a12

• Updated@parcel/diagnostic@2.0.0-nightly.177+db7e3a12

• Updated@parcel/events@2.0.0-nightly.177+db7e3a12

• Updated@parcel/fs@2.0.0-nightly.177+db7e3a12

• Updated@parcel/logger@2.0.0-nightly.177+db7e3a12

• Updated@parcel/package-manager@2.0.0-nightly.177+db7e3a12

• Updated@parcel/plugin@2.0.0-nightly.177+db7e3a12

• Updated@parcel/types@2.0.0-nightly.177+db7e3a12

• Updated@parcel/utils@2.0.0-nightly.177+db7e3a12

• Updated@parcel/workers@2.0.0-nightly.177+db7e3a12